KR20180100143A - Manufacturing method of artificial wood board - Google Patents

Abstract

The present invention relates to a method for manufacturing an artificial wood panel. More specifically, the present invention relates to a method for producing artificial wood board which is highly durable, inexpensive, and environmentally friendly. Furthermore, the present invention relates to an artificial wood board obtainable by the method of the present invention.

Description

Manufacturing method of artificial wood board

The present invention relates to a method for manufacturing an artificial wood panel. Furthermore, the present invention relates to an artificial wood board obtainable by the method of the present invention.

Artificial wood boards, also commonly known as particleboard or fibreboard, may be used as wood particles, such as wood particles, such as wood chips, sawmill wood chips, sawdust and fibers, such as hemp, fennel, jute, lt; RTI ID = 0.0 > cereal straw. < / RTI > These wood particles are typically pressed and bonded together using chemical binders. There are several types of artificial wood boards with different board densities; Particleboard (low density), medium density fiberboard, also known as MDF, and hardboard. These wood boards, especially MDF, are often used in the building and furniture industries.

The manufacturing process of the wood board consists of binding the fibers together using a binder, and pressing them into the final product. First, the raw material used is milled with particles or fibers, and then the particles are dried. A resin or binder is then sprayed onto the particles to obtain a mixture of particles and binder. The binder is used to bond the particles together or " glue " the woodblock, the final product. The mixture is then formed into a sheet and subsequently the mixture is squeezed at a temperature of 140 ° C to 220 ° C at 20 bar to 30 bar. This process cures and hardens the adhesive (binder) and binds the particles / fibers of the material. Finally, the board can be cooled, polished and sanded and ready for use.

The binder is typically a thermosetting or heat-curing resin, often made from toxic formaldehyde. The type of binder used plays an important role in determining the characteristics of the final product. Amino-formaldehyde-based resins are the best performing materials when considering cost and ease of use. The urea phenolic formaldehyde resin and the urea melamine resin are used to provide moisture resistance, and the increased melamine provides enhanced resistance of the woodblock. Generally, in the woodblock manufacturing process, fibers are combined using urea-formaldehyde (UF) and phenol-formaldehyde (PF) resins due to their low cost and the effective physical-mechanical properties they provide to the final product. For example, UF resins are primarily used in the MDF industry due to their low cost and fast curing characteristics.

A disadvantage of using UF and PF resins in the manufacture of woodblocks is that they are not environmentally friendly and unsafe for use due to the health effects of exposure to formaldehyde emissions and potential problems associated with formaldehyde emissions. PF resins are more durable and do not release formaldehyde, but the use of PF resins is more costly than UF resins, and PF resins have a much slower cure rate than UF resins. Moreover, formaldehyde-based resins derived from petrochemical processes do not last at all. The disadvantage of current wood boards is that they are very easy to swell and discolor due to moisture exposure. Therefore, the wood board is not suitable for construction in a moisture environment, and is rarely used in a place where outdoor or high level of water exists.

Rapid urbanization is creating a lack of traditional building construction materials due to limited availability of natural resources. On the other hand, the energy consumed in the manufacture of conventional building construction materials pollutes air, water and land. In order to meet the growing demand for energy efficient building construction materials, it is desired to adopt cost-effective, environmentally sound " green " technologies and redevelop typical technologies.

In view of the above, there is a need in the art for a method for manufacturing artificial wood board that is highly durable, low-cost, and environmentally friendly. This method should preferably result in a cost effective, non-contaminated preparation of high quality artificial wood, without the use of additional chemical binders.

The object of the present invention is to solve the above-mentioned needs in the art among other purposes. BRIEF DESCRIPTION OF THE DRAWINGS The objects of the present invention are fulfilled by the present invention, among other objects, as set forth in the appended claims.

Specifically, the object is fulfilled by the present invention by a method of manufacturing an artificial wood board according to the first aspect, among other purposes,

a) Milling the lignin-containing plant material to obtain a milled mixture;

b) Conditioning the milled mixture to obtain an equilibrium moisture content of 12% to 25%, preferably 16% to 25%;

c) Homogenizing the conditioned milled mixture;

d) Cold compressing the homogeneous mixture obtained in step c) to obtain a brittle board;

e) heat-compressing the brittle board to a density of 1.2 g / cm ³ to 1.4 g / cm ³ to obtain an artificial wood board

.

The artificial wood panels of the present invention are made from lignin-containing plant material, which is considered to be a " green " raw material. The lignin content of these substances is naturally high in certain plant materials. Binders used in the process of the present invention are all-natural products without added formaldehyde or other non-natural chemical binders.

Lignin is a class of complex organic polymers and is a major component in the supporting tissues of vascular plants and algae. Lignin in lignin-containing plant material is crosslinked with a thermosetting phenolic resin upon heating under high pressure. Whereby an organic particle board can be produced without adding a binder. Phenolic molecules in the lignin portion of the plant material have sufficient double covalent bonds and associated chemical reactivity to act as a thermosetting resin so that the plant material can be heat pressed into high quality artificial wood. The mechanical properties of the artificial wood are controlled by the degree of crosslinking of the lignin and the density of the material. The degree of crosslinking density depends on the temperature, pressure and moisture content during the thermal compression of the milled mixture used in the artificial wood manufacturing process. Increasing the degree of crosslinking will result in an increase in mechanical properties.

According to a preferred embodiment, the invention relates to a method of making artificial wood, wherein the lignin-containing plant material comprises particles having a particle size of less than 5 mm, preferably less than 2.5 mm, more preferably less than 2 mm .

According to another preferred embodiment, the present invention relates to a method of making artificial wood, wherein the lignin-containing plant material comprises a coconut crust husk pith. The coconut shell represents good waste suitable for the production of wooden boards. The lignin content in the coconut crust of the coconut crust is naturally at a high level; The lignin content in the medium is in the range of 40% to 50%, while the lignin content in the fibers is 30% to 35%. Coconut crustaceans are inexpensive, moth proof, resistant to fungi and decay, flame retardant, and have excellent temperature and sound insulation properties. The coconut crustaceans have high lignin and phenolic content and can be heated and compressed with artificial wood, where no artificial binder is added during manufacture. The naturally occurring chemicals in the crust of the crust allow it to be heated and compressed into a binder-free artificial wood.

According to a further preferred embodiment, the invention relates to a method of making artificial wood, wherein the lignin-containing plant material comprises fresh plant material of less than 6 months old. The peculiar lignin in plant material plays an important role in the hardening of artificial wood. Too dry material loses phenolic resin behavior that provides thermosetting properties to the final board.

According to a preferred embodiment, the invention relates to a process for the production of artificial wood panels, wherein the lignin-containing plant material comprises a water content of 12% to 25%, preferably 16% to 25%. Moisture content has several effects during the manufacture of artificial wood. The curing process at a water content of about 12% resulted in an overly dry board containing more non-cured material than the board made from lignin-containing plant material with a moisture content of about 16%. However, too high a water content causes blistering due to rapid water vaporization and limits the density that can be achieved during hot pressing of the brittle board. This is probably due to excessive physical particle displacements due to excess water present in the brittle board. On the other hand, too low a water content inhibits the viscoplastic flow of the particles during hot compression, resulting in a low degree of crosslinking by limiting the density due to the lack of proximity between the reacting molecules. The moisture content of lignin-containing plant material of 16% to 25% showed the highest quality of artificial wood in terms of maximum density, best flexural modulus and strength. The moisture content of the raw material is directly related to the selected time and thickness to be produced. A high moisture content ensures a higher conductivity and thus shortens the time required for the sample to reach the curing temperature. However, high moisture content can cause vapor explosions during pressure release and create heterogeneity that ultimately affects the final properties of the material.

According to another preferred embodiment, the present invention relates to a method of making artificial wood, wherein the equilibrium moisture content is adjusted by adding water to the milled mixture to obtain said equilibrium moisture content.

According to yet another preferred embodiment, the invention relates to a method of making an artificial wood, wherein after step e, the artificial wood is conditioned under static pressure for at least 24 hours to form- A wooden board is obtained. Wood boards are vulnerable to deformation induced by moisture absorption during reconditioning. Thus, the wood block is held under a static mass using a static load horizontal wise immediately after the heating and compression. In this way, the board will be form-stable.

According to a preferred embodiment, the invention relates to a process for the production of artificial wood, wherein in step d the homogeneous mixture is cold-pressed such that the thickness is at least 1: 3, A brittle board is obtained that is at least 1: 4, more preferably at least 1: 5, and most preferably at least 1: 6. A homogeneous mixture prior to compression cooling has a density of 0.1-0.25 g / cm ^3, preferably from about 0.2 g / cm ^3. After cooling compressed, brittle board has a density of 0.3-0.6 g / cm ^3, preferably 0.35-0.45 g / cm ^3.

According to the present invention relating to the method of manufacturing an artificial wood board, step e is a total maximum of 1 minute to 4 minutes per 1 mm layer thickness of the brittle board, preferably 1 to 3 minutes per 1 mm layer thickness of the brittle board, More preferably 1.5 minutes to 2 minutes per 1 mm layer thickness of the brittle board. The timing of step e affects the balance between the matrix to be dried at its moisture content by evaporation, the time required for the reaction to complete, and the cooling time for the material to cool homogeneously.

According to yet another preferred embodiment, the present invention relates to a process wherein step e is carried out at a temperature of from 140 캜 to 220 캜, preferably from 150 캜 to 200 캜, more preferably from 160 캜 to 180 캜.

The temperature is an essential variable in heat compression to achieve optimal flow and chemical crosslinking of the particles. The temperature of the brittle board must exceed 140 ° C during crosslinking; The lignin reacts (or hardens) at a temperature higher than 140 ° C and chemically bonds with the organic compound surrounding the lignin. However, in order to minimize the time in the hot press and accelerate the process, a temperature of 160 캜 to 180 캜 is preferable. Using a temperature higher than 220 ° C may pose a risk of damage to artificial wood finishes due to blistering or charring. The temperature can also influence the viscosity of the lignin, thereby reducing the viscosity, allowing it to flow through the porous medium and bond homogeneously to the fibers.

According to the present invention relating to the method for producing artificial wood, step e is carried out at a pressure of 120 to 170 bar, preferably 130 to 160 bar, most preferably 140 to 150 bar. This pressure is necessary to fix particles of the brittle board close enough that the phenolic molecules can bond and " bond " together. Pressure is a major driver for closely contacting the lignin and matrix as well as allowing the lignin to flow and fill all the cavities. The lignin and matrix facilitate the creation of more crosslinking points, and thus the bonding and strength of the material. The most optimal pressure chosen is the result of two phenomena playing an important role: the first is the high viscosity of the lignin that must flow through the very narrow channels of the matrix to increase the pressure drop; The second phenomenon is the short distance between the lignin and the fibers needed to ensure the reaction of the final product and thus the strength.

According to another preferred embodiment, the present invention relates to a process according to the invention, wherein said conditioned milled mixture obtained in step b is mixed with other wood-like substances and / or additives and / or polymers and / or cement- Based composition. (For example, water-resistant, flame retardant, mold resistant, etc., or different finishes such as matt or glossy appearance) of the product and even more sustained In order to develop a possible product, a mixture of several natural and chemical additives such as wheat gluten, soy protein, milk casein, vegetable oil, citric acid, furfural, wax, dye, wetting agent and / Lt; / RTI >

According to a second aspect, the present invention relates to an artificial wood board obtainable by the method of the present invention.

According to a further preferred embodiment of the present invention, the bending strength of the artificial wood panel is at least 46 N / mm ² , preferably at least 47 N / mm ² . The mixture of particles obtained from the milling of the lignin-containing plant material has staple fibers incorporated into the mixture. These fibers affect the flexural strength of the artificial wood board. Flexural stiffness is the best indicator of the processing quality of lignin-containing plant material.

According to the invention, the artificial wood panel has a moisture content of 12% to 25%, preferably 16% to 25%, and the artificial wood according to the invention is immersed in aqueous solution for 24 hours in accordance with European standard EN 317 , And a thickness swelling of 13% or less, preferably 12% or less, more preferably 10% or less, and most preferably 9% or less due to moisture absorption.

According to another preferred embodiment of the present invention, the artificial wood panel has an internal bonding strength of 1.8 N / mm ² or more, preferably 2.2 N / mm ² or more, more preferably 2.5 N / mm ² or more, At least 25% v / v to 50% v / v of coir dust.

Compared to a high density fiberboard (HDF), also referred to as a hardboard (HB), the artificial wood board of the present invention has improved features. The artificial wood board of the present invention conforms to the European standard EN622-2 and belongs to the category: "hard board for load bearing and wet conditions" (type HB.HLA1).

According to a further preferred embodiment of the invention, the artificial wood panel comprises a composition comprising lignin-containing plant material mixed with other wood-like materials, additives and / or polymers and / or cement-based compositions. The artificial wood boards of the present invention may contain several natural and chemical additives such as wheat gluten, soy protein, milk casein, vegetable oil, citric acid and / or furfural Can be developed. The artificial wood board of the present invention may contain various other chemicals including waxes, dyes, wetting agents, and release agents to obtain products that are highly water-resistant, refractory, and insoluble.

The present invention will be further described in the following examples.

Example 1 Milling

Fresh coconut shells (less than 6 months old) were imported from Indonesia. To preserve the freshness of the crust, it was stored in a plastic bag in a conditioned room at 95% relative humidity (RH) and 28 < 0 > C. Thereafter, about 2 kg of coconut shells were sawed into smaller portions and milled using FRITSCH Model 15.302 / 694 in three different steps (no sieve, 10 mm sheave, 2 mm sheave) Respectively. The end result is a mixture of dust and fibers sieved at 2 mm.

Example 2 Conditioning and moisture content

The milled coconut coir was conditioned in two different atmospheres: RH 50%, 24 ° C and 65% RH, depending on the moisture content of the milled coconut coir, for a period of 5 days to 12 days at 20 ° C. The wet sample was then weighed, dried in an oven at < RTI ID = 0.0 > 103 C < / RTI > for at least 18 hours and finally the dry sample was verified by weighing according to the following formula:

Here, " mw " and " md " are wet weight and dry weight, respectively.

Example 3 Production of wood board

The process includes the following steps:

One. Coarse conditioning

2. Preliminary compression

3. Heat compression

4. Conditioning under static pressure

5. Trimming

6. Board conditioning

1. Coir conditioning

Perform this step until the target equilibrium moisture content (EMC) is reached.

2. Preliminary compression

To reach a final density of 1.35 g / cm < ³ >, conditioned cocoa is loaded into a mold. After uniformly spreading the coiler, the mold was compressed to 0.15 ton / cm < ² > for 1 minute. In this case, 69.8 g of coir is loaded in a 10 x 15 cm steel mold at 22.5 tons for 1 minute.

3. Heat compression

The result of the precompression step is a brittle board called " Prepack ". The prepared " prepack " was placed between two aluminum plates of 1.6 mm thickness and compressed for 4 minutes at 170 ° C and 22.5 tonnes (0.15 ton / cm ² ), including the heating up time. The sample was then cooled inside the press until an internal temperature of 50 ° C was measured using a thermocouple.

4. First conditioning under static pressure

The prepared board was conditioned under mass overnight at room temperature.

5. Trim

To remove the dry-non-cured-material, trimming of the sample was performed after the first conditioning and before the second conditioning.

6. Second Conditioning

The conditioned samples were conditioned at 65% RH and 20 ° C until the mass did not change more than 0.01% according to the European standard EN 310, for example to obtain a morphologically stable product. To maintain flatness, the samples were placed on a support with the mass on top of the samples.

Example 4 Identification of Physical-Mechanical Properties of Artificial Wood Board

After reaching a stable weight, the sample was cut into two 50x50 mm squares and one 2x8 mm strip. The prepared samples were tested according to the European standard EN 622-2. These standards include all the tests needed to compare an artificial wood board to a high density fiberboard (HDF), also known as hardboard (HB). A list of specific tests is provided below.

Exam Name European standard Check density EN 322 After immersing in water for 24 hours, the swelling thickness EN 317 Bending strength, flexural modulus EN 310 Inner bond EN 319 Internal bond after test EN 319 - EN1087-1

Table 1. Tests performed on artificial wood boards in accordance with European standards.

result

Eleven artificial wood board samples were tested according to European standards as described above. Samples 1 to 5, 10 and 11 have a moisture content of 16.4%, and Samples 6 to 9 have a moisture content of 12%.

density

Density measurements were performed in duplicate on samples 1, 2, 3, 4, 8, 9, 10 and 11 according to European standard EN 322.

sample Weight (g) Height (mm) Width (mm) Thickness (mm) Density (g / cm ³ ) 1.1 10,71 50, 26 49,98 3.03 1,41 1.2 11,38 50,29 50,33 3.22 1,40 2.1 10,92 50,41 50,40 3.06 1,40 2.2 10.97 50,52 50,35 3,10 1,39 3.1 10.87 50,42 50,44 3.08 1,39 3.2 10.78 50,39 50,29 3.05 1,40 4.1 10,94 50,51 50,37 3.11 1,38 4.2 10,51 50,28 50,79 2.98 1,38 8.1 10,65 50, 23 50,21 3,036 1,39 8.2 11.04 50, 26 50, 23 3,113 1,40 9.1 10.7 50,33 50,14 3.03 1,40 9.2 10,89 50,03 50,29 3.08 1,41 10.1 10,54 48.05 49,23 3.19 1,40 10.2 10,58 48,92 49,34 3.13 1,40 11.1 10,23 48,80 49,69 3.01 1,40 11.2 10.31 48,99 49,86 3,00 1,41 Average 10,863 50,328 50,318 3,073 1,40

Table 3. Density measurement of artificial wood board samples

Bending strength and flexural modulus

The bending strength and flexural modulus tests were carried out on all samples according to the European standard EN310.

sample Bending strength (N / mm²) Flexural modulus (N / mm²) 1.3 46,28 4156,44 2.3 46,37 4221,63 3.3 47,99 4217,41 4.3 45,68 6944, 53 5.1 46.83 4409,03 5.2 46,22 4419,26 Average 16,4% 46, 56 4728,05 6.1 47.85 4660.25 6.2 45,39 4601,92 6.3 46,54 4590,80 7.1 47,29 4387,31 7.2 38,89 3625,64 7.3 41,30 3757.09 8.3 39,26 3790,51 9.3 46,99 4233,77 Average 12% 44,19 4205,91

Table 4. Bending strength and flexural modulus of artificial wood board samples

Inner bond, and inner bond after the boil test

Inner bond, and inner bond after the boil test were performed on Samples 1 to 4 in accordance with EN319 and EN1087-1.

sample Strength (N / mm ² ) Sample after boil test Strength (N / mm ² ) 1.1 2,61 1.2 2.03 2.1 1,69 2.2 1,64 3.1 2.15 3.2 1,21 4.1 3.96 4.2 1,59 Average 2,60 1,61

Table 5. Inner bond, and inner bond after boil test of artificial wood sample.

Thickness swelling after immersion in water for 24 hours

This test was carried out on the following samples according to the European standard EN 317.

sample Weight (g) Height (mm) Width (mm) Thickness (mm) Swelling (%) 8.1 11.77 50,88 50,94 3,413 12,4% 8.2 12,10 50.87 50,81 3,505 12,6% 9.1 11.86 50,98 50,82 3,417 12,8% 9.2 11,96 50,76 50,91 3,465 12.5% 10.1 11.49 48,64 49.84 3,485 9,1% 10.2 11,48 49.49 50,02 3,482 11,1% 11.1 11,24 49,51 50,24 3,382 12.5% 11.2 11,32 49,68 50, 56 3,382 12,6%

Table 6. Measurement of thickness swelling after immersion in water.

Claims (19)

A method of manufacturing an artificial wood board,
a) milling a lignin-containing plant material to obtain a milled mixture;
b) conditioning the milled mixture to obtain an equilibrium moisture content of 12% to 25%, preferably 16% to 25%;
c) homogenizing the conditioned milled mixture;
d) cold compressing the homogeneous mixture obtained in step c) to obtain a brittle board;
e) heat-compressing the brittle board to a density of 1.2 g / cm ³ to 1.4 g / cm ³ to obtain an artificial wood board
≪ / RTI > The method according to claim 1,
Wherein the lignin-containing plant material comprises particles having a particle size of less than 5 mm, preferably less than 2.5 mm, more preferably less than 2 mm. 3. The method according to claim 1 or 2,
Wherein the lignin-containing plant material comprises a coconut husk pith. 4. The method according to any one of claims 1 to 3,
Wherein the lignin-containing plant material comprises less than 6 months old fresh plant material. 5. The method according to any one of claims 1 to 4,
Wherein the lignin-containing plant material comprises a water content of 12% to 25%, preferably 16% to 25%. 6. The method according to any one of claims 1 to 5,
The equilibrium moisture content is adjusted by adding water to the milled mixture to obtain the equilibrium moisture content. 7. The method according to any one of claims 1 to 6,
After step e, the artificial wood is conditioned under static pressure for at least 24 hours to obtain a form-stable artificial wood board. 8. The method according to any one of claims 1 to 7,
In step d, the homogeneous mixture is cold-pressed so that it is at least 1: 3, preferably at least 1: 4, more preferably at least 1: 5, most preferably at least 1: A brittle board having a thickness of at least 1: 6 is obtained. 9. The method according to any one of claims 1 to 8,
The step e may be carried out for a total of 1 minute to 4 minutes per 1 mm layer thickness of the brittle board, preferably 1 to 3 minutes per 1 mm layer thickness of the brittle board, more preferably 1 mm layer Lt; RTI ID = 0.0 > 1.5 < / RTI > minutes to 2 minutes. 10. The method according to any one of claims 1 to 9,
Wherein step (e) is carried out at a temperature of from 140 캜 to 220 캜, preferably from 150 캜 to 200 캜, more preferably from 160 캜 to 180 캜. 11. The method according to any one of claims 1 to 10,
Said step e being carried out at a pressure of from 120 bar to 170 bar, preferably from 130 bar to 160 bar, most preferably from 140 bar to 150 bar. 12. The method according to any one of claims 1 to 11,
Wherein the conditioned milled mixture obtained in step b) is mixed with other wood-like materials and / or additives and / or polymers and / or cement-based compositions. An artificial wood board obtainable by the manufacturing method according to any one of claims 1 to 12. 14. The method of claim 13,
Wherein said artificial wood board has a bending strength of 46 N / mm ² or more, preferably 47 N / mm ² or more. The method according to claim 13 or 14,
Said artificial wood panel having a water content of 12% to 25%, preferably 16% to 25%. 16. The method according to any one of claims 13 to 15,
Preferably less than 12%, more preferably less than 10%, most preferably less than 9% due to water absorption after being immersed in an aqueous solution according to European standard EN 317 for 24 hours, Of thickness swell. ≪ Desc / Clms Page number 13 > 17. The method according to any one of claims 13 to 16,
Wherein the artificial wood board has an internal bonding strength of 1.8 N / mm ² or more, preferably 2.2 N / mm ² or more, and more preferably 2.5 N / mm ² or more. 18. The method according to any one of claims 13 to 17,
Wherein said artificial wood board comprises at least 25% v / v to 50% v / v coir dust. 19. The method according to any one of claims 13 to 18,
Wherein the artificial wood board comprises a lignin-containing plant material mixed with other wood-like materials and / or additives and / or polymers and / or cement-based compositions.